PH Testing device



FIG. 1 is a plan view of the pH testing device showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a side elevational view thereof;

FIG. 5 is an elevational view showing the opposite side;

FIG. 6 is a bottom view thereof.

The ornamental design for a pH testing device, as shown.